The preparation of a hypertonic salt water solution for immediate use as a gargle and mouthwash is a well-known treatment and preventative for infections of the mouth and throat. Salt water will reduce swollen tissues and draw infection from any abscesses or infections present. Bacteria are single-celled organisms which can multiply rapidly under conditions found in the pharyngeal or buccal cavity. When the reproductive rate of certain strains of bacteria outstrips the immune response, soreness, inflammation, and even fever can result. While some bacteria are actually beneficial to the human body pathogenic bacteria are often directly responsible for many human illnesses, with one of the most common human illnesses being a sore throat.
Gargling with hypertonic salt water causes osmosis to occur. Osmosis is the process by which solvents, such as water, separated by a semi-permeable membrane, move from a region of lower concentration to higher concentration in order to equilibrate. By introducing hypertonic saline into the pharyngeal or buccal cavity, bacterial dehydration and lysis occurs.
Inflammation, regardless of the cause, is also reduced as water is drawn from tissues by osmosis. Hypertonic saline solution also helps to draw liquid from the throat. Edemas naturally occur during an infection, and by drawing it out of the tissue, swelling is reduced. This in turn reduces pain.
The salt may also kill some bacteria, but many strains are now resistant to mild levels of salt. It is a misconception to think that the salt water will directly kill off the bacteria. Gargling or rinsing with hypertonic saline solution simply creates a dehydrated environment that the bacteria find less hospitable and potentially dangerous and has implicated in reducing biofilm formation by Pseudomonas aeruginosa and the production of associated virulence factors. Hypertonic saline also appears to increase the levels of two thiols that are protective against oxidative injury namely, glutathione and thiocyanate.
Unfortunately, diluted hypertonic saline ready for use as a mouthwash or gargle is a growth medium for halophilic organisms that include algae, fungi, and bacteria. Exemplary organism include Dunaliella Halobacteria, Halorhabdus, and Eurotiomycetes. As a result, the production and storage of a hypertonic saline of a concentration suitable as a mouth wash or gargle is problematic. While such solutions can be pasteurized or radiation sterilized for single use applications, such techniques are both expensive and ineffective a multiple use container is contemplated. As an alternative, low molecular weight, synthetic organic molecules have been used as antimicrobials to afford storage stability. Unfortunately, a number of people have sensitivity to such antimicrobials, while still others find the flavor profile of antimicrobials unpleasant. Additionally, the usage of such antimicrobials has raised concerns about downstream effects on the environment and induction of resistance in target microbes.
Additionally, a certain class of individuals, including those with hypertension cannot safely use a saline rinse. As a result, for such individuals to treat the pharyngeal or buccal cavity for infections, hydrogen peroxide is often used. While 3% hydrogen peroxide in water has stability of greater than one year in a sealed container, opening such a bottle decreases the shelf life. Also, metal ions present in the solution, leached from a container, or introduced through contamination induce catalytic decomposition to water.
Thus, there exists a need for a mouth wash and gargle solutions that are prepared at ready to use concentrations that have storage stability without resort to small molecule synthetic antimicrobials.